1. Field of the Invention
The invention relates to a non-destructive process for estimating the ageing of an article made of a composite material, and is applicable to all articles made of an organic composite material comprising a fibre-reinforced resin.
The life of an article made of an organic composite material depends upon the conditions in which it is used and, in particular, upon the thermal cycles to which it is subjected during use. Large and repetitive temperature variations applied to an organic composite material lead to a loss of material due mainly to degradation of the resin, this loss of material being accompanied by a weight loss and a loss of the mechanical properties of the composite material. In particular, the interlaminar and intralaminar shear forces increase, the breaking strength decreases and the longitudinal modulus of elasticity decreases. For safety reasons, particularly in the aviation field, an article made of a composite material must be replaced when the weight loss reaches 3% of the initial weight. It is therefore essential to be able to estimate the life of articles made of composite material and to be able to evaluate their age in terms of mechanical properties.
2. Summary of the Prior Art
At present, in order to determine the weight loss of an article made of a composite material, samples of the material are cut from the article and then chemically attacked to determine the proportions of each constituent, namely the fibres and the resin, of the composite material and to deduce from this determination the weight loss of the article. The disadvantage of this operation is that the article is destroyed by the taking of material samples and so cannot be used as often as would be desirable.